I know they sound awesome. But why do some companies introduce them? What are you suggesting introducing them for? To combat burnout. I.e. hopefully shortly before someone really burns out or most probably after they burned out already and need recovery they can go on a sabbatical.
How about not doing 80 hour weeks in the first place? How about not using arbitrary deadlines and throwing a fit over minor delays or changes to the plan? How about not doing all the crazy preventable things and pawing it off on other people.
I know, might be too much to ask so to speak but I really wish that more people would just not take this abuse instead of asking for a sabbatical to recover from the abuse.
Anyway, my $0.02.